This invention relates to a lubricating system for an oil seal packing mounted to a portion of an input shaft of a manual transmission which extends through a wall of a transmission case.
In feeding a lubricant to the oil seal packing mounted to the rotary input shaft of a manual transmission, it has hitherto been usual practice to feed the lubricant from outside instead of forming oil grooves inside the input shaft. When this feeding method is employed, lubricant flowing toward a sealed portion of the input shaft from outside begins to swirl about the input shaft as it draws nearer to the input shaft, and tends to be thrown away therefrom by centrifugal forces produced by an increase in the speed of its swirling. Owing to this phenomenon, difficulties have been experienced in lubricating the sealed portion satisfactorily. To solve this problem, the applicant of this invention has made a proposal to provide an improved lubricating system, as disclosed in Japanese Utility Model Application Laid-Open No. 13377/77, which comprises a plurality of radial grooves or fins located radially outside of the sealed portion of the input shaft and oriented toward the center of the input shaft, to avoid the lubricant swirling about the rotating input shaft and allow the same to be forced by gravitational pull to drop on to the sealed portion.
This system of the prior art is considered to have some effect in feeding the lubricant satisfactorily to the sealed portion of the input shaft by preventing the lubricant from swirling about the rotating input shaft and from being adversely affected by the centrifugal forces. However, it has been found, as a result of the use of this method of the prior art, that practically effective grooves or fins for lubrication are, among many grooves or fins, only those which are located just above the sealed surface.